Ensure that compiler is disabled now by checking its status:

Flush Magento cache

Very often installation of new extensions with Compilation Mode enabled breaks your site. You cannot view the front-end and back-end. Nothing works. In this case the only solution is to disable Compilation Mode to get the site back to normal state.

Now you can get into your back-end. If you need to enable the Compilation mode again you should use „Run Compilation“ button and NOT just enable it again (as it will break your site again). Running it will compile all new files correctly.

or the other way

FTP/Filemanager/Filesystem

delete includes directory or rename it to any other name (_includes.unused for example):